trnF Sequences Research Articles

Evolution of the south-western Pacific genus Melicytus (Violaceae): evidence from DNA sequence data, cytology and sex expression

Phylogenetic analyses of nuclear DNA external transcribed spacer (ETS) and chloroplast DNA trnL–trnF markers were undertaken to reconstruct the evolutionary history of the South Pacific genus Melicytus. Bayesian analyses of the ETS sequence data produced a phylogenetic tree with several well supported groups, including clades comprising: (1) species from Australia, Tasmania and Lord Howe Island; (2) the Norfolk Island M. latifolius and New Zealand off-shore island M. novae-zelandiae subsp. novae-zelandiae; (3) the large-leaved M. ramiflorus complex; (4) M. fasciger and M. micranthus; and (5) M. obovatus and allies from the Cook Strait region. Phylogenetic analysis of trnL–trnF sequence data also retrieved some of these groups although, in general, was not as well resolved. The relationships of M. lanceolatus are equivocal, as in the ETS phylogeny it is sister to a clade comprising the large-leaved tree species M. fasciger and M. ramiflorus complex and the small-leaved M. micranthus, whereas in the trnL–trnF phylogeny it is sister to a clade of small-leaved shrub species such as M. alpinus and M. crassifolius. Several biogeographic patterns are evident, with dispersal to the west from New Zealand, to Australia, involving small-leaved shrub species. Dispersal to the north from New Zealand, to Norfolk Island and Fiji, involves large-leaved tree species. The sex expression is documented for all named species and undescribed entities, with these being either hermaphroditic or dioecious. When sex expression is mapped onto the phylogeny, the hermaphroditic system is inferred to have evolved from the dioecious system. New chromosome counts are presented for M. angustifolius (2n = 64) and M. dentatus (2n = 32), and earlier counts of 2n = 64 are confirmed for M. crassifolius and M. alpinus. An additional 17 counts are provided for two natural hybrids and several undescribed entities from Australia and New Zealand. The polyploid chromosome number of 2n = 64 occurs most frequently in small-leaved divariate plants with hermaphroditic flowers. When chromosome numbers are plotted onto the phylogeny it is inferred that high polyploids (e.g. 2n = 64) and small-leaved shrubs have evolved from large-leaved trees with functional diploid (e.g. 2n = 32) chromosome numbers.

Phylogenetic relationships in subtribe Poinae (Poaceae, Poeae) based on nuclear ITS and plastidtrnT–trnL–trnF sequencesThis paper is one of a selection of papers published in the Special Issue on Systematics Research.

The worldwide temperate subtribe Poinae comprises the largest grass genus, Poa (500+ species), and multiple additional small genera. We explore generic boundaries and relationships among genera of Poinae using nuclear ribosomal internal transcribed spacer data (ITS) and plastid trnT–trnL–trnF (TLF) sequence data. ITS and TLF analyses are mostly congruent with regards to circumscription of genera, and with respect to relationships among Poinae genera, but tree structure is generally better supported among genera in the ITS strict consensus tree. ITS and TLF both support two main Poinae lineages: (i) Poa and (ii) a clade comprising all other sampled Poinae. Nine small genera were nested within the large Poa clade, including Aphanelytrum , Dissanthelium , and Tovarochloa , supporting inclusion of these as sections within Poa. In the second clade, three subclades support close relationships among Nicoraepoa , Hookerochloa , and Arctagrostis ; Arctophila and Dupontia ; and Apera , Bellardiochloa , and Ventenata . Genera of the related subtribes Alopecurinae, Cinninae, and Miliinae were mixed among or in part external to Poinae in different ways in ITS and TLF analyses, and only subtribe Puccinelliinae was strongly supported and monophyletic. ITS analyses supported placement of Catabrosella , Hyalopoa , and Paracolpodium in Puccinelliinae (no TLF data available). The position of Poa subgenus Arctopoa is incongruent between the two analyses: TLF data support inclusion within Poa and ITS data place it outside of Poa. Similarly, TLF data resolves the genus Aniselytron outside of Poa, whereas ITS data place it within Poa. Based on these results and a consideration of morphology, we recognize Arctopoa and Aniselytron as genera, probably of ancient hybrid origins. Nothogenus × Duarctopoa is coined for Arctopoa × Dupontia, with a single nothospecies × Duarctopoa labradorica . A new combination is provided for Poa subg. Sylvestres .

Molecular systematics and biogeography of Resedaceae based on ITS and trnL-F sequences

The Resedaceae, containing 6 genera and ca. 85 species, are widely distributed in the Old World, with a major center of species diversity in the Mediterranean basin. Phylogenetic analyses of ITS and plastid trnL– trnF sequences of 66 species from all genera of the Resedaceae reveal (1) monophyly of the family, in congruence with preliminary phylogenetic studies; (2) molecular support for the traditional morphological subdivision of the Resedaceae into three tribes according to ovary and placentation types, and carpel number; (3) two monophyletic genera ( Caylusea, Sesamoides), and one natural group (core Reseda), which includes the remaining four genera of the family ( Ochradenus, Oligomeris, Randonia, Reseda); (4) a monophyletic origin for four of the six taxonomic sections recognized within Reseda ( Leucoreseda, Luteola, Glaucoreseda, Phyteuma). Our results lead us to interpret an increment of the basic chromosome number in the family from x = 5 to x = 6 in at least two independent instances, and a broad representation of polyploids in multiple lineages across phylogenies, including association between octoploids and alien invasion in many parts of the world. Species diversity, endemism number, phylogenetic relationships and sequence divergence in Resedaceae suggest two major centers of differentiation, one in the western Mediterranean, and the other in the eastern Mediterranean and SW Asia. Two independent colonization events to the Canary Islands from Africa are indicated for the two Canarian Reseda endemics.

Phylogenetic biogeography of the leafy liverwort Herbertus (Jungermanniales, Herbertaceae) based on nuclear and chloroplast DNA sequence data: correlation between genetic variation and geographical distribution

AbstractAim The cosmopolitan genus Herbertus is notorious for having a difficult taxonomy and for the fact that there is limited knowledge of species ranges and relationships. Topologies generated from variable molecular markers are used to discuss biogeographical patterns in Herbertus and to compare them with the geological history of continents and outcomes reported for other land plants.Location Africa, Asia, Azores, Europe, southern South America, northern South America, North America, New Zealand.Methods Phylogenetic analyses of nuclear ribosomal internal transcribed spacer and chloroplast (cp) trnL–trnF sequences of 66 accessions of Herbertus and the outgroup species Triandrophyllum subtrifidum and Mastigophora diclados were used to investigate biogeographical patterns in Herbertus. Areas of putative endemism were defined based on the distribution of species included in the analyses. Maximum parsimony analyses were undertaken to reconstruct ancestral areas and intraspecies migration routes.Results The analyses reveal species‐level cladograms with a correlation between genetic variation and the geographical distribution of the related accessions. The southern South American Herbertus runcinatus is sister to the remainder of the genus, which is split into two main clades. One contains the Neotropical–African Herbertus juniperoideus and the New Zealand/Tasmanian Herbertus oldfieldianus. An African accession of H. juniperoideus is nested within Neotropical accessions. The second main clade includes species that inhabit Asia, the Holarctic, Africa, and northern South America. Maximum parsimony analyses indicate that this clade arose in Asia. Herbertus sendtneri originated in Asia and subsequently colonized the Holarctic and northern South America. An Asian origin and colonization into Africa is indicated for H. dicranus.Main conclusions The current distribution of Herbertus cannot be explained by Gondwanan vicariance. A more feasible explanation of the range is a combination of short‐distance dispersal, rare long‐distance dispersal events (especially into regions that faced floral displacements as a result of climatic changes) extinction, recolonization, and diversification. The African Herbertus flora is a mixture of Asian and Neotropical elements. Southern South America harbours an isolated species. The molecular data indicate partial decoupling of molecular and morphological variation in Herbertus. Biogeographical patterns in Herbertus are not dissimilar to those of other groups of bryophytes, but elucidation of the geographical ranges requires a molecular approach. Some patterns could be the result of maintenance of Herbertus in the inner Tropics during glacial maxima, and dispersal into temperate regions in warm phases.

Phylogeny of Eleusine (Poaceae: Chloridoideae) based on nuclear ITS and plastid trnT– trnF sequences

Phylogenetic relationships in the genus Eleusine (Poaceae: Chloridoideae) were investigated using nuclear ITS and plastid trnT– trnF sequences. Separate and combined data sets were analyzed using parsimony, distance, and likelihood based methods, including Bayesian. Data congruence was examined using character and topological measures. Significant data heterogeneity was detected, but there was little conflict in the topological substructure measures for triplets and quartets, and resolution and clade support increased in the combined analysis. Data incongruence may be a result of noise and insufficient information in the slower evolving trnT– trnF. Monophyly of Eleusine is strongly supported in all analyses, but basal relationships in the genus remain uncertain. There is good support for a CAIK clade ( E. coracana subsp. coracana and africana, E. indica, and E. kigeziensis), with E. tristachya as its sister group. Two putative ITS homeologues (A and B loci) were identified in the allotetraploid E. coracana; the ‘B’ locus sequence type was not found in the remaining species. Eleusine coracana and its putative ‘A’ genome donor, the diploid E. indica, are confirmed close allies, but sequence data contradicts the hypothesis that E. floccifolia is its second genome donor. The ‘B’ genome donor remains unidentified and may be extinct.

Investigation of the phylogenetic relationships within the genus Citrus (Rutaceae) and related species in Korea using plastid trnL- trnF sequences

The phylogenetic relationships within the genus Citrus and related species found in Korea were analyzed by comparing the trnL- trnF intergenic spacer sequences of the chloroplast DNA (cpDNA). All 21 accessions had trnL- trnF sequences of identical length, 372 base pairs (bp). Of the 377 aligned positions in the trnL- trnF regions of these species, 67 sites were variable (17.8%, 67/377). Pairwise sequence divergences in the trnL- trnF region ranged from 0 to 3.2% in the ingroup accessions and from 8.8 to 10.9% between the in- and the outgroup species Phellodendron amurense. The greatest divergence (3.2%) was between C. aurantium and C. natsudaidai. A phylogenetic tree was generated based on maximum parsimony (MP) analysis of the trnL- trnF sequences data from 22 accessions, including the outgroup taxon, producing 17 equally most parsimonious trees. The consensus tree contained eight independent clusters. Cluster I contained C. platymamma, which has a collared fruit shape, unique among Korean Citrus. Cluster II contained mostly mandarin and pummelo accessions. Cluster V contained C. sunki and six accessions of C. unshiu. Four of six C. unshiu accessions had identical sequences. In addition, Nagami kumquat ( Fortunella margarita) was phylogenetically close to Citrus, whereas the trifoliate orange ( Poncirus trifoliate) was distant from Korean Citrus species, both local species and cultivars. These results confirmed that analyses of cpDNA trnL- trnF sequences can detect enough polymorphisms to differentiate Korean Citrus species and to determine their phylogenetic relationships.

Phylogenetic relationships in Monanthes (Crassulaceae) based on morphological, chloroplast and nuclear DNA variation

AbstractPhylogenetic relationships of all 10 recognized taxa of the genus Monanthes which is endemic to the Canary Islands and Salvage Islands, were investigated using the four data sets: morphology, sequences of the chloroplast DNA trnL (UAA) — trnF (GAA) intergenic spacer, ITS2 sequences of the nuclear ribosomal region and Random Amplified Polymorphic DNAs (RAPDs). In contrast to the molecular data, the morphological data were internally inconsistent which probably resulted from parallel or convergent evolution of morphological characters. The molecular data sets indicated that the genus is not monophyletic due to inclusion of the annual M. icterica which is the putative sister taxon of Aichryson, that M. polyphylla is the sister taxon of the perennial species of the genus, that M. muralis from Hierro is of allotetraploid origin and that M. lowei, M. minima, M. brachycaulos, M. laxiflora, M. anagensis and M. muralis from La Palma are closely related. Combined ITS2 sequences, trnL — trnF sequences and morphological data indicated that the relationships among three types of perennial growth forms, i.e. tiny rosettes, small, branched shrubs and diffuse branches shrublets, are highly dependent on the outgroup used. After deletion of the most distant outgroup and a taxon of alleged hybrid origin (M. muralis) relationships among the growth forms of Monanthes still could not be consistently resolved.